The present invention relates to an information providing system. More particularly, the present invention relates to an information management apparatus capable of reliable management of distributed information and an information providing system employing the same information management apparatus.
Advanced computerization has promoted the establishment of various information providing systems, such as the Dial Q2 System using telephone lines.
When an information providing system provides copyrighted pieces of information, such as musical works or motion pictures, the reliability of management of the copyrights of the information is one of the important factors that determine the economical feasibility of the information providing system. Particularly, when the information providing system provides information represented by digital signals, the importance of the reliability of copyright management is even more significant because digital signals can be copied without entailing significant signal degradation. A method of inhibiting the copying of information, as disclosed in Japanese Patent Laid-open (Kokai) No. 1-288582, mixes false signals for causing the automatic gain control system of VTRs to malfunction into the digital signals representing the information to degrade the quality of pictures copied on recording tapes.
On the other hand, in a country where cable television broadcasting systems are widespread, such as the U.S.A., it is possible to develop information providing systems that provide digital signals representing information desired by subscribers, such as video software, and to use the cable television broadcasting systems as information transfer means. Newly released films are particularly high-valued matters of video software. When providing such high-valued matters of video software, it is essential to establish a highly intelligent information management system which is capable of limiting the number of reproducing cycles, as well as inhibiting copying. The aforesaid known method of inhibiting copying information is incapable of dealing with limiting the number of reproducing cycles.